1. Field of the Invention
This invention relates to a printed circuit board device having a structure for positioning a plurality of printed circuit boards on each other.
2. Description of the Related Art
The conventional positioning structure for use in connecting printed circuit boards with each other is shown in FIGS. 10 and 11. To electrically connect a first flexible printed circuit board 21 and a second flexible printed circuit board 22, it is the common method that nail plate-like projection pieces 24 for interconnection formed in the second flexible printed circuit board 22 are superimposed on respective exposed copper foil patches 23 for interconnection on the first flexible printed circuit board 21 and then heaped with solder 25. Since, at this time, positioning must be made to establish good registry between the patches 23 and the pieces 24 in each pair, a pair of positioning dowels 27 are erected on a support plate 26 for the first board 21. The two boards 21 and 22, on the other hand, are provided with two positioning holes 28 and 29 arranged so that when both boards 21 and 22 are superimposed with the holes 28 and 29 fitted on the dowels 27, a good positional relationship is automatically established in each pair of the aforesaid exposed copper foil patch 23 for interconnection and the aforesaid nail plate-like projection piece 24 for interconnection.
In the conventional example described above, because, in addition to the two flexible printed circuit boards to be connected, there is need to employ the support plate member on which the positioning dowels are provided, and because every one of the aforesaid two boards has to have two positioning holes, there are the following drawbacks:
(1) If the support plate member on which the positioning dowels are provided is not disposed in appropriate locations, another member on which the positioning dowels are provided must be prepared. This leads to an increase in the number of parts. PA1 (2) The necessity of forming two positioning holes in each of the paired flexible printed circuit boards to be connected results in a complicated structure of the connector portions of every one of both boards. To cope with this complexity, the flexible printed circuit board has to increase in size and, therefore, in production cost. PA1 (3) The density of installation is lowered by an amount equal to the size of the additional space occupied by the positioning holes and their reinforcing neighborhood. PA1 (4) A high precision accuracy is required for making up the two positioning holes in each of the printed circuit boards in prescribed relation to each other and to both of the exposed copper foil patch of the first board and the projection piece of the second board. Therefore, the production cost of the flexible printed circuit boards increases greatly.